import math
a,b,c,d = map(float, input().split(' '))
t = (a - c)**2
h = (b - d)**2
z = t + h
print(math.sqrt(z)) import math math a,b,c,d = map(float, input().split(' ')) a map(float, input().split(' ')) map float input().split(' ') ().split () input split ' ' b c d t = (a - c)**2 t (a - c)**2 a - c a c 2 h = (b - d)**2 h (b - d)**2 b - d b d 2 z = t + h z t + h t h print(math.sqrt(z)) print math.sqrt(z) math.sqrt math sqrt z b,c,d = map(float, input().split(' ')) map(float, input().split(' ')) b t = (a - c)**2 (a - c)**2 t c,d = map(float, input().split(' ')) map(float, input().split(' ')) c a,b,c,d = map(float, input().split(' ')) map(float, input().split(' ')) a z = t + h t + h z h = (b - d)**2 (b - d)**2 h d = map(float, input().split(' ')) map(float, input().split(' ')) d
import math
a,b,c,d = map(float, input().split(' '))
t = (a - c)**2
h = (b - d)**2
z = t + h
print(math.sqrt(z))
